Systematic induction of superconductivity in the Cu(Y1-xCa x)Ba2Cu2O6+δ (δ ≈ 0.3) system by Ca substitution

V. P.S. Awana*, M. A. Ansari, Rashmi Nigam, Anurag Gupta, S. B. Samanta, R. B. Saxena, H. Kishan, V. Ganesan, A. V. Narlikar, M. Arai, M. Karppinen, H. Yamauchi, Devendra Buddhikot, S. K. Malik

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

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Series of samples of the composition Cu(Y1-xCa x)Ba2Cu3O6+δ (δ ≈ 0.3) have been prepared by a solid-state synthesis route. Precise oxygen content was determined for all the samples by iodometric titration. The c lattice parameter increases with increasing x, indicating successful substitution of Y3+ by the bigger Ca2+ ion. Resistivity (R) versus temperature (T) measurements show that the pristine sample (x = 0.0) is semiconducting down to 5 K. Induction of superconductivity is seen with increasing x. The x = 0.10 sample exhibits the onset of superconducting transition (Tconset) at 42 K without attaining a zero resistance superconducting transition temperature (TcR=0) state above 5 K. For the x = 0.15 and 0.20 samples TcR=0 is observed at 25 and 35 K with Tconset at 52 and 61 K, respectively. DC magnetic susceptibility measurements corroborated the findings from the resistivity measurements. Thermoelectric power (S) measurements in the temperature range of 5-300 K exhibit Tcs=0 at 25 and 35 K respectively for x = 0.15 and 0.20 samples. The room-temperature 5 value decreases with increasing x, indicating an enhanced number of mobile holes. Magneto-transport measurements in applied magnetic fields of 3 and 6 T show a broadening of the superconducting transition. These results will be useful in constructing a more complete phase diagram of the Cu(Y1-xCa x)Ba2Cu3O6+δ system in terms of x and 5.

Original languageEnglish
Pages (from-to)716-720
Number of pages5
JournalSuperconductor Science and Technology
Issue number5
Publication statusPublished - 1 May 2005
MoE publication typeA1 Journal article-refereed


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